Explain the following terms:

Frequency distribution, Class frequency, Class limits, Class interval, Class mark, Frequency curve.

Frequency distribution : It is a comprehensive way to classify raw data of a quantitative variable. It shows how the different values of a variable are distributed in different classes alongwith their class frequencies.

Class frequency : It means the number of values in a particular class.

Class limit : Each unit in a frequency distribution table is bounded by class limits. Class limits are the two ends of a class. The lowest value is called the lower class limit and the highest value, the upper class limit.

Class interval: Class interval or class width is the difference between the upper class limit and the lower class limit.

Class mark : The class mid-point or class mark is the middle value of a class. It lies half way between the lower class limit and the upper class limit of a class.

Clas mark or class mid point =  Upper Class limit  + Lower Class Limit
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Frequency Curve : It is a graphic representation of a frequency distribution. To obtain the frequency curve we plot the class marks on the X-axis and frequency on the Y-axis.